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Constraining the Nature of the Galactic Center X-ray Source Population

S. Laycock·J. Grindlay·M. van den Berg·P. Zhao·J. Hong·X. Koenig·E. M. Schlegel·S. E. Persson
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Abstract

We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from stellar companions, their X-ray properties are consistent with magnetic Cataclysmic Variables, or High Mass X-ray Binaries (HMXB) at low accretion-rates. A direct way to decide between these possibilities and hence between alternative formation scenarios is to measure or constrain the luminosity distribution of the companions. Using infrared (J, H, K, Br-gamma) imaging, we searched for counterparts corresponding to typical HMXB secondaries: spectral type B0V with K<15 at the GCR. We found no significant excess of bright stars in Chandra error circles, indicating that HMXBs are not the dominant X-ray source population, and account for fewer than 10% of the hardest X-ray sources.

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S. Laycock, J. Grindlay, M. van den Berg, P. Zhao, J. Hong, X. Koenig, E. M. Schlegel, S. E. Persson. 2005-09-26. Constraining the Nature of the Galactic Center X-ray Source Population. https://doi.org/10.1086/498821

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